火灾下碳纤维布加固钢筋混凝土梁非线性分析

Nonlinear Analysis of Insulated Carbon-Fiber-Reinforced-Polymer Strengthened

摘要:

在合理选取混凝土、钢筋及碳纤维布力学性能参数的基础上，建立了带防火保护的碳纤维加固混凝土梁高温下的数值计算模型，应用ANSYS软件编制了碳纤维加固钢筋混凝土梁火灾下非线性有限元分析程序NFACCB，实现了加固梁火灾下的热力学耦合分析。分析结果表明：采用合理的防火保护，加固梁可以获得较好的耐火性能；防火材料厚度 和火灾载荷比k对加固梁耐火性能有显著影响；纵筋配筋率n、碳纤维加固量m、防火材料导热系数以及截面尺寸也对火灾下的加固梁挠度产生影响；而加固梁挠度随防火材料的比热和容重的变化不明显。

关键词:钢筋混凝土梁;碳纤维加固;防火保护;有限元模型;热力学耦合

Abstract:

Based on the reliable models of mechanical properties degradation of concrete, reinforcing steel and Carbon Fiber-Reinforced-Polymer (CFRP) materials with increasing temperature were accounted for in this current analysis, this paper established the numerical model of insulated CFRP-strengthened reinforced concrete beams and compiled a nonlinear finite element method (FEM) program (named NFACCB) of strengthened beams under exposure of fire event using general-purpose code ANSYS, and also developed the coupled thermo-mechanical analysis. The simulated results are shown that, although CFRPs are sensitive to elevated temperature, satisfactory fire performance behaviour can be achieved by providing reasonably supplemental fire insulation. Moreover, it is demonstrated that fire insulation thickness and fire load ratio have a significant effect on fire performance of strengthened beams, that longitudinal bar reinforcement, amount of CFRP strengthening, thermal conductivity of insulation materials and sectional dimension have only moderate influences, and that mid-span deformations versus thermal specific heat and density are not obvious.

Key words:RC beam; CFRP-strengthening; fire insulation; finite element model; coupled thermo-mechanical analysis